PHY 2049 Midterm: University of Florida PHY 2049 exam2sol
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Exam 2 solutions: a current i travels in the direction of the arrows shown in the figure in three wire segments. The straight segments (upper left and upper right in the figure) both are lined up with the center point, p, which is the center of the circular arc segment wire shown which subtends (takes up) an angle of 120o. Solution: the current in the straight wires that would go thru center point p if extended contributes zero to the field (as discussed in lecture for chap. The field at the center of a circular arc of wire (eq. 29-9) is b= 0i /(4 r), where is the angle taken up by the circular arc. 120o is 1/3 of 360o, where 360o is 2 radians, so 120o=(1/3) 2 radians, so. B= 0i /(4 r)= = 0i(2/3) /(4 r)= 0i/(6r): 0i/(12r, 0i/(3r, 0i/(2r, 0i/(4r, consider the toroid shown in the figure.
